| Summary: | Mid-ocean ridge magmatism is driven by seafloor spreading and decompression melting of the upper mantle. Melt production is apparently modulated by glacial-interglacial changes in sea level, raising the possibility that magmatic flux acts as a negative feedback on ice-sheet size. The timing of melt variability is poorly constrained, however, precluding a clear link between ridge magmatism and Pleistocene climate transitions. Here we present well-dated sedimentary records from the East Pacific Rise that show evidence of enhanced hydrothermal activity during the last two glacial terminations. We suggest that glacial maxima and lowering of sea level caused anomalous melting in the upper mantle and that the subsequent magmatic anomalies promoted deglaciation through the release of mantle heat and carbon at mid-ocean ridges. © 2016 American Association for the Advancement of Science. 14 September 2015; accepted 6 January 2016. We dedicate this paper to J. Dymond, whose 1981 treatise on Nazca plate sediments made this work possible. We are also indebted to the Oregon State University Core Repository for carefully preserving the EPR sediment cores since they were collected in the early 1970s. We are grateful to L. Wingate at the University of Michigan and M. Cote at the University of Connecticut for technical support. This work has benefited from discussions with J. Granger, P. Vlahos, B. Fitzgerald, and M. Lyle. Data presented here are available on the National Oceanic and Atmospheric Administration's Paleoclimatology Data website (www.ncdc.noaa.gov/data-access/paleoclimatology-data). Funding was provided by the University of Michigan and the University of Connecticut. Supplemental Material - aad4296-Lund-SM-table-S1.xlsx Supplemental Material - aad4296-Lund-SM-table-S2.xlsx Supplemental Material - aad4296-Lund-SM-table-S3.xlsx Supplemental Material - aad4296-Lund-SM-table-S4.xlsx Supplemental Material - aad4296-Lund-SM-table-S5.xlsx Supplemental Material - aad4296-Lund-SM.pdf
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